(PhysOrg.com) -- A team of researchers from the NIST Center for Nanoscale Science and Technology and FEI Company have adapted a commercial focused ion beam (FIB) column to use photoionized laser-cooled lithium atoms as an ion source, and demonstrated that NISTs patented Magneto-Optical Trap Ion Source (MOTIS) offers imaging performance competitive with the liquid metal ion sources used in most FIBs.

In a MOTIS, a gas of atoms is laser-cooled to ≈ 100 μK and then photoionized. The ions are accelerated to the desired energy, forming a highly monochromatic beam that is amenable to nanoscale focusing when provided as input to a commercial focused ion beam column. The light mass and low surface sputtering rate of laser-cooled lithium allowed the researchers to demonstrate non-destructive imaging with a characteristic focal spot size of 26.7 nm ± 1.0 nm at 2 kV.

As predicted theoretically, the focal spot size was shown to depend on the temperature of the laser-cooled atoms and on the ion beam energy. The researchers anticipate further improvements to the system spot size for enhanced imaging. These results demonstrate that NISTs new ion source may enable a wide range of new applications  from nanoscale imaging and defect metrology to ion implantation and material modification.